1. Technical Field
The present invention relates to organopolysiloxane and method for the preparation thereof. More specifically, the present invention relates to organopolysiloxane (i) that has monofunctional siloxane units (M unit) and tetrafunctional siloxane units (Q unit). (ii) that contains in each molecule at least one epoxy group-containing organic group, and (iii) that contains in each molecule at least one diorganopolysiloxane residue bonded therein through a divalent hydrocarbon group.
2. Prior Art
Various types of MQ organopolysiloxanes are already known in the art. Shirahata in U.S. Pat. No. 4,707,531, issued Nov. 17, 1987, describes a method of making MQ organopolysiloxanes which have long been used as starting materials for varnishes and pressure sensitive adhesives. According to Shirahata an alkyl silicate is dripped into a mixture of an aqueous hydrochloric acid which contains at least 5 weight percent hydrogen chloride and a trialkylsilane or a disiloxane at a temperature of 0.degree. to 90.degree. C. Shirahata and Fukutani in U.S. Pat. No. 4,946,921, issued Aug. 7, 1990, describe a hydroxyphenyl-containing MQ organopolysiloxane of the general formula ##STR1## where A is a hydroxyphenyl group. R' is an alkylene group having 1 to 4 carbon atoms, n is zero or one. R" is an alkyl group having 1 to 4 carbon atoms, x and z are positive numbers y is zero or a positive number, x, y, and z have values such that their ratios are 0.ltoreq.(x+y)/z.ltoreq.4, and zero.ltoreq.y/x.ltoreq.5.
Fukutani in U.S. Pat. No. 5,011,901, issued Apr. 30, 1991, describes a chloromethyl-containing MQ organopolysiloxane of the general formula ##STR2## where R' is a monovalent hydrocarbon group having 1 to 6 carbon atoms, R" is a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, x and y are positive numbers, y is zero or a positive number, and x, y, and z have values such that their ratios are 0.3.ltoreq.(x+y)/z.ltoreq.4 and zero.ltoreq.y/x.ltoreq.100.
However, the groups bonded to the silicon in the monofunctional siloxane units (M unit) of these MQ organopolysiloxanes are limited to the hydrogen atom, alkyl, alkenyl hydroxyphenyl, and chloromethyl. There have been no reports of MQ organopolysiloxane in which the silicon in the monofunctional siloxane unit (M unit) carries both an epoxy-containing organic group and a polydiorganosiloxane residue bonded thereto through a divalent hydrocarbon group.
The present invention was developed as the result of extensive investigations by the present inventor in order to solve the preceding problem.